QueryServiceObjectSecurity

[DllImport("Advapi32.dll", SetLastError = true)][return: MarshalAs(UnmanagedType.Bool)]
public static extern bool QueryServiceObjectSecurity(
   IntPtr hService,
   uint dwSecurityInformation,
   byte[] lpSecurityDescriptor,
   uint cbBufSize,
   out uint pcbBytesNeeded
);

Microsoft documentation: Link